The initial call setup time will "increase slightly" when Direct Connect users are on a 1xRTT connection, though the service will run the same once the call is established, Sprint said.

Before Sprint opened Direct Connect to its 1xRTT network, the devices needed to connect to Sprint's 3G EVDO network. Sprint's 3G coverage is concentrated in urban centers, while its 2G network spans sparsely populated rural areas.

The additional coverage provided by the 1xRTT service will be important to customers Sprint is trying to move to Direct Connect, as they tend to work in remote areas outside of 3G coverage.

Sprint is working to switch customers to Direct Connect so it can tear down its money-losing iDEN network, slated to close as early as June 30, 2013. It has stopped selling iDEN phones on its website and is phasing them out of stores.

The company is on track to take 9,600 iDEN cell sites off the air by the end of the third quarter and has hired Goodman Networks, Pyramid Network Services, WesTower Communications, and Black & Veatch construction affiliate Overland Contracting to negotiate lease termination agreements, restore cell site compounds and remove Sprint network equipment for reuse or recycling.

The 800 MHz spectrum left over from iDEN will be used to add capacity to Sprint's LTE network, currently running in its 1900 MHz holdings.